Upstream bioprocess modeling is a critical tool for optimizing and understanding cell growth, measuring nutrient consumption, and assessing the impact of process parameters on cell culture performance. However, traditional growth models focus on growth, stationery, and lag phases failing to capture decay phase, limiting the understanding of the complete cycle. This paper proposes utilizing a two-tailed asymmetrical growth-decay curve (TTAGDeC), capturing both growth and decay phases, allowing for more accurate modeling in diverse scenarios. To address the time and cost challenges of extensive data collection, particularly for long cell growth curves, a variable interval sampling function (VISF) is proposed. Here, data is collected dynamically based on the rate of change, potentially reducing sampling frequency while maintaining model accuracy. By combining the TTAGDeC curve with VISF, this study proposes a cost-effective and informative strategy for modeling bioprocess dynamics, facilitating improved understanding and optimization of cell culture performance. The applicability of the proposed approach is illustrated in the culture of Escherichia coli.